Pursuing Veritas

Of course, John’s commitments to theological accuracy, Qur’anic accuracy, and intellectual integrity did not prevent him from discerning Islam’s status as heresy. For John, Islam’s core doctrines represented a departure from true Christian teaching. He viewed Islam existing within the same basic religious framework, though as an alternative to Christian orthodoxy, a competitor to the truth that worshiped the same God while misunderstanding His nature and revelation. This is most obviously evident in how John includes Islam in his catalogue of heresies, treating it as a theological error rather than an entirely separate faith. This categorization is reinforced in the Disputatio, where he addresses Islam as a theological deviation rather than an external threat.

Today, heresy carries the pejorative connotations it has accrued through years of (mis)use. Originally, however, the term simply denoted a theological perspective outside the realm of the acceptable (Edwards 2023: 1.2). Peter Schadler has argued that John’s perspective on Islam was a minority view in his own day, in no small part due to the imperialization of Christianity and history of heresy catalogues (Schadler 2018: 20-48). And yet the reality of heresy as a differentiation did not entirely fade away. Indeed, this way of thinking lasted well into the modern era, with even someone like G.K. Chesterton denoting Islam’s heretical status as late as 1917 (Chesterton 2012: 56).

Thus, heresy still bore with it a descriptive sense along with the pejorative. For John, Islam was a heresy in need of theological correction, not an essential distinct faith or wholly external threat. This underscores John’s commitment to accuracy and integrity in treating Islam: this was a deviation where correct was possible, an ill to be cured, not a cancer to be cut off. Daniel Sahas has convincingly demonstrated how John used standard terminology for Christian heretics to describe Muhammad and Islam, highlighting John’s view of Islam as a serious doctrinal misstep rather than a completely alien belief system (Sahas 1972: 69).

John’s fundamental critiques of Islam focus on its failure to recognize the Trinity and its portrayal of Christ as merely human, underscoring his perception of Islam as a distorted form of Christianity. For John, Islam was chiefly distinguished by its failure to worship Father, Son, and Spirit in Trinity and Unity, a reality rooted in inaccurate understandings of the Christian God which extended into the Qur’an itself (Griffith 2008: 30). By casting Islam as a heresy—belief rooted in an inaccurate understanding of God—John’s critique of Islam was fundamentally theological in nature.

Summary

Peri Haereson and Disputatio demonstrate considerable awareness of Islamic thought in a perhaps surprisingly positive light. In contrast to the sloppy prooftexting and rhetorical drama that often appear in heresy catalogues and mock-dialogues, John consistently employs accurate portrayals of Islamic doctrine and practice. In the words of John Renard, ‘John seems quite intent on informing Christian readers about Islamic beliefs and practice, not to inflame them against their Muslim neighbors’ (Renard 2011: xx). Islam was clearly a heresy for John, a distorted worldview that propagated Christological errors. And yet Islam was not so very different than Christianity, certainly not distinct enough to be viewed as wholly other category of belief like Roman paganism or Judaism.

To summarize, for John of Damascus, Islam should be understood accurately as a means of theological correction and differentiation. Islam was not wholly other than Christianity; but neither was it the same. Parsing Islam required careful familiarity with claims and prooftexts as well as accurate assessment in order to ensure that Christians did not fall into theological error.